Synopsis
Recognise calcium-related neurological, renal and cardiac toxicity, restore safe volume, suppress tumour-driven calcium release, identify the biological mechanism and prevent recurrent metabolic deterioration.
- Malignant hypercalcaemia commonly results from PTHrP secretion, osteolytic metastases or myeloma, and less often calcitriol-producing lymphoma; mechanisms may overlap.
- Symptoms include thirst, polyuria, dehydration, constipation, nausea, weakness, cognitive change and shortened-QT or rhythm disturbance; severity depends on rate of rise as well as the number.
- First-line confirmation is repeat albumin-adjusted calcium, or ionised calcium when protein binding is unreliable, with renal function, phosphate, magnesium and ECG in severe disease.
Key red flags
Confusion, reduced consciousness, seizure or profound weakness with raised calcium indicates neurological toxicity and needs monitored treatment.
Lethargy, proximal weakness, confusion, agitation, reduced consciousness or seizure reflects important neurological effect and may progress rapidly.
Investigation priorities
Confirm true elevation, assess trajectory and avoid protein-binding artefact.
Management branches
Confirmed hypercalcaemia causes symptoms, dehydration, renal injury or cardiac concern.
- Use ABCDE assessment, ECG, neurological examination and accurate fluid balance; repeat calcium and companion electrolytes and stop avoidable calcium-raising medicines and supplements.
- Give intravenous 0.9% sodium chloride in reassessed stages, adapting each prescription to pressure, urine, sodium, lungs, age and cardiac or renal reserve.
Key medicines
Intravenous 0.9% sodium chlorideUse the staged volume and infusion rate in the current Society for Endocrinology and local acute-oncology pathway, reassessing after each prescription for blood pressure, urine output, sodium, lung signs and cardiac or renal tolerance.
Zoledronic acidFor an adult with tumour-induced hypercalcaemia and albumin-corrected calcium at least 3.0 mmol/L, give a single 4 mg intravenous infusion over no less than 15 minutes after adequate hydration and renal assessment.